Comment 1 for bug 839562

I'm not sure how we're gonna fix this, PortAudio doesn't expose any functions to change port numbering with JACK (it only gives functions for changing the client name). Additionally, it seems that the counter used to number our jack ports isn't ever reset -- every time the jack connection is reopened, the numbers increase. This may require some work on the portaudio jack implementation.

> There may also be a very similar issue with the numbering policy in Mixxx preferences. Ports are numbered 1/2, 2/3, 3/4 and so on. Should they be 1/2, 3/4, 5/6 ... ? There may be a reason for this in terms of Jack operation and port setup policy but I'm not sure.

This is done to accommodate monaural devices. For instance you might have a 1 channel input (a mic for instance) at channel one and then a stereo input at channels 2 and 3. If the numbering wasn't done like this, you'd be unable to configure this setup.